sphinx: Configure sys.path to allow autodoc to find Kazoo.

Previously, if Kazoo wasn't already in sys.path otherwise (e.g. if not
installed) sphinx autodoc wouldn't be able to find the module for
documenting purposes because sphinx-build happens in an adjacent
subdirectory.

This adds the docs folder's parent to the path so that autodoc can find
the Kazoo module properly and do its stuff.
Merge pull request #115 from nailor/master

Limit the backends we use for SLF4J
add missing changelog entry
update a bunch of dependency versions for development
prepare
vb
fix the socket timeout, _session_timeout is ms
fix typo in attribute name
LockingQueue documentation update
Merge pull request #121 from xpahos/master

LockingQueue documentation update
tweak message for #121 and add changelog entry
Merge pull request #114 from spladug/autodoc-sys.path

sphinx: Configure sys.path to allow autodoc to find Kazoo.
Point to new location and update to gevent 1.0rc3, closes #123
Fix `KazooRetry.copy` to correctly copy sleep function, closes #126.

The introduction of the new `ignore_expire` argument changed the positional
order of arguments. Use keyword arguments!
Fix command retry typo in client
try to fix gevent 0.13.8 installation while keeping 1.03c3 working
Merge pull request #128 from cosbynator/master

Fix command retry typo in client
add changelog entry for #128
also tell travis to use gevent 1.0rc3
Merge pull request #118 from novas0x2a/fixes

a few minor fixes